单选题
Scientists have been puzzled for decades by how turtles manage to navigate across the Atlantic — but now they know. The creatures have their own inbuilt magnetic compass. A laboratory experiment has revealed that the tiny turtles are born with the ability to "detect" the magnetic fields which help them to navigate the 8,000 miles across the stormy Atlantic Ocean and back home again. After hatching from eggs laid in nests along beaches in Florida, baby turtles swim out into this current and flow with it for years, nudged along by warm waters rich in food. They seem to use both the intensity and direction of the magnetic field to navigate. It is also found that turtles born in the Pacific are genetically imprinted with a different magnetic map for currents from those in the Atlantic. They would soon perish in the Atlantic.
单选题
Scientists didn't know decades of years ago that ______. A. turtles have their own inbuilt magnetic compass B. what kind of compass is built in turtles' body C. what kind of map turtles use in navigating D. why turtles don't die in the Atlantic
【正确答案】
A
【答案解析】[解析] 事实细节题。从文章的第一段可知，“在过去科学家不知道海龟是如何渡过大西洋的”，最后一句解释了原因：The creatures have their own in built magnetic compass．所以答案选A。
单选题
Scientists' findings are based on ______. A. their research on the Atlantic B. their research on the Pacific C. their study on the magnetic field D. their experiments done in labs
【正确答案】
D
【答案解析】[解析] 事实细节题。从第二段的第一句可知，“实验室研究证明……”，即A laboratory experiment has revealed that...，从这句话可以判断答案选D。
单选题
Turtles ______. A. learn to navigate as they grow up B. know how to detect the magnetic field when they are bom C. can only navigate across the Atlantic D. start their navigation when they grow up
单选题
It can be inferred that ______. A. turtles navigate with a compass B. turtles only make use of the direction of the magnetic field C. turtles will eventually go back to the place where they are born D. scientists have different opinions as to how turtles make their way home
【正确答案】
C
【答案解析】[解析] 判断推理题。A项从第一段的最后一句可知是错的，扭曲了那句话的意思；B项从第四段的第一句话They seem to use both the intensity and direction...可知是错的，具有片面性；D项文中并没有提及，属于无中生有，也是错的；而根据第四段的第二句可以推断C是正确的，所以答案选C。
单选题
According to the last paragraph, some turtles may die in the Atlantic ______. A. if they are not strong enough B. because they are not old enough C. because the Atlantic is very stormy D. as they are born the Pacific
【正确答案】
D
【答案解析】[解析] 判断推理题。从最后一段第二句和第三句turtles born in Pacific are genetically imprinted with a different magnetic map..., they would soon perish in the Atlantic(出生在太平洋的海龟与那些在大西洋出生的海龟有着不同的磁场地图印记，他们可能在大西洋很快就死去)，可知答案选D。